A coke plant normally has a battery of coking chambers of rectangular horizontal outline that are separated from one another by heated walls defining their longer sides and are open at their two narrower ends. These ends are provided with doorjambs against which respective coke-oven doors can sealingly fit during the coking process to hold the charge in the respective chamber and to prevent the escape of gases and heat from the chamber. These doors, as described on pages 120 ff. of The Making, Shaping and Treating of Steel by H. McGannon (Herbick & Hood: 1971), each have a rigid panel with a periphery complementary to the respective doorjamb. A seal is provided at this periphery for forming a gastight connection between the periphery and the doorjamb, and holding means serve to press the door tightly onto the respective doorjamb. Mounted on the inner face of this panel is a vertically elongated and horizontally projecting plug of refractory insulating material that extends into the respective coking chamber. The insulating plug protects the door from overheating while similarly preventing the ends of the charge inside the chamber from being inadequately coked because of excessive cooling. Gases generated during the coking process normally are drawn off from the space formed between the upper level of the charge and the roof of the chamber.
The plugs normally project some 400 mm from the iron door frames into the chambers and are generally formed from interfitting refractory bricks which are very heavy and relatively expensive to mount in place and maintain. Normally the chambers also have a refractory lining that projects outward roughly to the level of the refractory lining of the door, leaving a gap. As this gap fills with particulate material during use, it must be meticulously cleaned after each coking process.
In order to reduce the gas pressure acting upon the door during a coking process, there has been proposed in accordance with U.S. Pat. No. 4,086,145 to Joseph M. Muller a coke-oven door provided with a generally flat metallic barrier spaced inward from its frame. The barrier, which is covered by a thermally insulating protective layer, holds the charge separated from the door frame while facilitating the rise of evolving gases. After escaping into the collection manifold, these gases must be quenched so that their heat content is uselessly dissipated.